The proposed research will investigate collection techniques and analysis of skin surface lipids (sebum) as a non-invasive quantitative means of assessing body burden of halogenated hydrocarbon residues. Compounds such as PCB, PBB, DDE and similar, environmentally derived perticide residues are stored mainly in adipose tissue. Current techniques to directly sample adipose tissue are invasive, involving either surgical biopsy or percutaneous needle aspiration of fat. While well-tolerated by most adults, these tests may be uncomfortable and are costly in terms of professional time, special facilities and equipment. With the growing recognition of the possible adverse effects of agents which bio-accumulate, a simple, non-invasive means of reliably and reproducibly assessing body burden of such residues is highly desirable. Over the past three years, the Environmental Sciences Laboratory has through research clinical studies and individual patient requests performed over 3000 analyses to assess exposure to halogenated hydrocarbons of environmental origin. Because of the unique opportunity of having as many as 300 subjects per year who for various reasons are undergoing adipose tissue sampling, serum testing and complete medical evaluation, the validity of the proposed technique can readily be evaluated by correlation of skin and hair oil levels with adipose tissue and serum levels. Initial observations in our laboratory of 35 subjects suggest that the proposed technique is feasible. Skin or hair oil measurements were correlated with serum concentrations of DDE, PCB, and PBB. The proposed research will refine the collection technique, which was not considered reliable in pilot studies. Other independent reports have confirmed that xenobiotics can be detected in skin or hair oil, and animal studies with PCB and PBB have shown that skin and hair are major reservoirs of storage, second only to adipose tissue. Although the present study will be directed toward nonpolar residues, the application of the technique for determination of other physiological chemicals will be possible.